I still remember the web when I got my first modem. What the ads changed is the amount of various clickbaits, useless sites, sites "for fun", garbage of the internet. All this would be gone without ad revenue, there wouldnt be any sustainable bussiness model for them.

Regarding usability of ads, in 20 years I never bought anything shown. When I need something I search for relevant product solving my need and I buy it. And trying very hard to avoid fake reviews. If your product type showed on ads is what I need, I will still do my best to check the market and find best product type for me with lowest price I can get. Which is typically not what is shown on ad. At the end they dont change anything for me.

Now the question is - would internet without ads really be that bad?

My personal expierience with one of the news sites (cant remember which it was) after GDPR was somehow refreshing. If you didnt agree, they disabled all javascript and throw you into same website but with only text and images relevant to the article. I loved it.